Voids and bubbles, 6. Flow LinesThe most simple design modification for eliminating the weakening effect of a weld line is to increase the wall thickness in the weld line zone (Figure 4). It has larger cross-sectional regions that allow sufficient molten plastic flow into the cavity. 030 0. Weld line location. Mold vents should function the same way. Meanwhile, Using more advanced cooling method such as cyclic cooling or conformal cooling. In this way critical areas of the interface in regard to the lack of interdiffusion and the inappropriate molecular orientation were found to be placed near. It is normally at the meeting points of two flow fonts. Weld lines appear as a result of the flow of molten plastic during the injection molding process. Figure 1 below shows the development of a weld line. Adjust the design for the flow pattern to be a single source flow. Weld line formation in the injection molding process occurs. In this study the polycarbonate (PC) and carbon fiber (CF) are used as the experimental materials to investigate the impact of injection molding process parameters on tensile strength of weld line. Despite injection molding being recognized as a robust process for obtaining parts with high geometry accuracy, one last occurrence remains a challenge in micro-injection molding, especially when junctions are. Heat/cool injection molding has a positive influence on the depth and visibility of weld lines. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. Conclusion The formation of weld lines in micro injection molding of plastic depends on different parameters such as melt temperature, injection pressure and fabrication method. For the production of these weld‐line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527‐2) and impact (ISO 179‐1/1eU. The conditions are temperature, injection speed, and injection pressure. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. Fisa et al. Change the gate locations so that the weld lines occur in locations less susceptible to external forces if weld strength is an issue. It occurs when melting plastic material is injected into a mold, it flows through all parts of th. Increasing the temperature of the mold or plastic material. Gates should be designed larger than normal and located to minimize weld line formation. Injection pressures too high Reduce pressure . Weld lines can affect both the aesthetics and mechanical properties of the product, making them a significant concern for. 1. Double push filling method. The thermo-rheological findings were used to investigate the sources of weld line weakness. Weld Lines. Weld lines are where two flow. This paper presents the. Usually it’s a straight line, and often to be found radiating. 1. If you adjust the ejection mechanism in the mold design, you also can reduce or eliminate your need for mold release agents. There is excess air inside the mold (1) make the mold vent larger at location with weld line; (2) Check if the mold vent is blocked or not or use vacuumized forming. Many researchers had emerged with several. In this study, polypropylene (PP) was compounded respectively with carbon nano fibers (CNFs) and TiO 2 nano particles at various weight fractions (10, 20, 30, 35. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. [ 18 - 21 ] In addition, the effects. Additionally, you can get our free Design Cube, which will provide a physical aid to help understand how knit lines form as well as other injection molding design considerations. To determine the effect of the weld lines on tensile strength, tensile tests were conducted with the specimens fabricated with NORYL (amorphous blends of. If the plasticizing ability of the plastics injection molding machine is insufficient, the plastic cannot be fully plasticized, resulting in weld lines when filling the mold. Thus, a right gate design raises polymer temperature to prevent the formation of weld lines and flow marks. Weld-Line in an injection molded part develops when two or more melt fronts are converged together. In the first, sequential injection moulding, the lines are displaced to noncritical areas of the moulding. This failure causes the product to be damaged during use. (2) Adjust the injection speed: high speed allows the melt to reach the confluence without cooling down, and low speed allows time for the air in the cavity to be discharged. Fellahi et al. This is particularly true if the wall thickness in the weld is thin – i. The difference between a weld and meld line is simply determined by the angle at which the converging flow fronts meet. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. For more information on the Factors Affecting the Injection Molding Process. * Corresponding author, e-mail: [email protected] recently had a few pieces (2-3%) crack after assembly, while in storage (not installed, still in the package). A knit line, also called a weld line, occurs when the liquid plastic moves through the mold and hits more melted plastic and they don’t flow or fuse together. Flow front tracing simulation results for weld line developing process in micro injection molding with Comsol ® Multiphysics 3. 1. You can expect a mold shrinkage percentage of. Flow-in-duced fiber orientation manifests in higher tensile properties in the direction of flow compared to normal to the direction of flow [13–15]. GlossFlow-induced fiber orientation and weld lines are com-mon features of the injection molding process. [ 18 - 21 ] In addition, the effects of flow behavior of the polymer melt due to the optimal process parameters for the minimization of weld-line effects are an important consideration. The literature on the formation of weld lines, and their consequences, is more abundant on the area of injection molding [5-12] than on extrusion [13]. 2017-01-0481. In this paper, a weld line computer determination method based on filling simulation with surface model is proposed, from which the positions and lengths of the weld lines can be predicted. Injection molds: (a) mold type A, (b) fixed plate of the mold type B, and (c) moving plate of mold type B The second mold (mo ld type B) was used for the ISO D2 specimen, as shown in Figure 2b,c . Abstract. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. In an injection molding process, a weld-line forms when two flow fronts meet each other. Short shots. Download : Download high-res image (856KB) Download : Download full-size image; Fig. A weld line is often unavoidable. Computer simulation packages of injection molding have had success in predicting filling behavior in extremely complicated geometries, capable of predicting weld lines’ location exactly. Numerical results show that weld lines can be predicted accurately, and the formation and evolution processes of weld line can be shown more clearly by co-injection molding technique. 004 m, a characteristic velocity ν 0 =0. Figure 1a illustrates how the weld line is produced when. Here are some strategies. Wu CY, Ku CC, Pai HY (2011) Injection molding optimization with weld line design constraint using distributed multi-population genetic algorithm. Knit and meld lines are inherent to plastic. In a meld line, the plastic comes together at an angle greater than 135 degrees. Molding calculation in Moldex3D: (а) melt front and weld line, (b). This paper evaluates the shrinkage and strength of weld line using Design of Experiment and Response Surface Methodology in multi-objective optimisation utilising the injection moulding parameters. The main types of injection molding defects are: 1. 2) show that the weld line is formed as expected from the middle of the cavity towards the wall. Weld lines are formed when there is an inability of two or more flow fronts to ‘knit’ or ‘weld,’ together during the molding process. In the case of PC, the model predicts satisfactorily the weld-line strength as a function of injection temperature. Weld lines can appear on the surface of a molded part where the molten material has converged after splitting off into two or more directions in a mold. Its appearance can be improved by adjusting parameters. This is expected to achieve maximum results while the pressure holding effect will also increase. Expand. The four sets of plaques are produced by changing the magnitude of packing pressure equal to 60% of filling pressure, with increment of 20% up to 120% of filling pressure. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms. Gate blush, 4. However, research about the computer determination of weld lines in injection molding remains scarce. Instead of using flow leaders and deflectors to control the locations of the weld lines, this paper presents an approach to specify the locations of the weld. Mold temperature controlInjection mold designers can alter the position of weld line by changing the gate locating. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. It is possible to pre. ) . Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. M. <Mold> Provide a cold slug well where weld lines occur. In this lesson we will focus on the meld and weld lines. when two or more melt flow fronts contact each other immediately after the cooling process. weld lines in infill analysis of injection molding simulation was observed [5]. Azieatul Azrin Dzulkipli and M. carried out to mass-produce molded products with complex shapes. 6. Gate location should set to avoid weld lines, keep clean of the important position of the products,. A weld or meld line on plastic parts can cause structural problems and/or be visibly unacceptable. [ 18 - 21 ] In addition, the effects of flow behavior of the polymer melt due to the optimal process parameters for the minimization of weld-line effects are an important consideration. Weld lines are among the most critical structural defects in parts made by the injection molding of fiber-reinforced thermoplastics, explained Sirmax in a press release. Increase the injection speed to reduce the amount of cooling happening in the mold. . 015 0. Poor mold spot Spot mold to ensure fit and vent depths at ~0 . Improvement of weld line strength in injection molded FRTP articles. A weld line is often unavoidable. Weld-line is a weak area which reduces the strength of the part locally. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. Injected plates were generated using a double-gated mold under four different process conditions. 2. Criens, R. Or increase the number of gates. The authors [5, 6] attempted to reduce the weld lines and clamping force of plastic injection moulding through numerical and experimental investigation, and discovered that the 3D cooling channel. Reduce the amount of release agents. Quality concerns in injection-molded materials can vary fr. 943 µm to 0. In this paper, a weld line factor (W-L factor) was adopted to. ac. A weld-line is known as a representative defect in the field of plastic injection moulding, and also as a cause of inferior mechanical propensities and poor appearance. Multiple gates are acceptable as long as they are close enough to each other to avoid weld line issues. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. The formation of weld line in the injection molding method is caused by the product and mold design that is one of the common mistakes. When an external load is applied to a weld line region, the part’s potential for mechanical failure is increased. The special injection mold is designed and fabricated to produce plaques having stagnation weld-line. One common issue that frequently arises during injection molding is the formation of weld lines. Weld. the three-plate mold often adopt this kind of gate. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. A knit line in a plastic injection-molded part is created when two separate plastic flows meet within the mold and "resolidify" along their interface. In Fig. 809-814. Weld line (also known as a knit line) is the line where two flow fronts meet when there is the inability of two or more flow fronts to “knit” together, or “weld,” during the molding process. Consultant @ Effinno Technologies, BSME, MBA - Bridge between Plastics Injection Molding Knowledge and Practice. Cracks in Corners – When cracks appear in the corners of plastic parts, the cause is too much plastic shrinkage onto the mold core in that corner. Second, depending on the size of the overflow well, you get a little bit of flow melding together, and that helps strength so that you have some intertwining of the polymer chains. In the 1947 book, Injection Molding of Plastics, the late Dr. a) Multi-fiber connector micro injection molding simulation b) 3D simulation of micro gear with 150µm diameter for weld line position prediction c) 3D micro injection molding filling simulation of micro gear with 180µm diameter Fig. 2. As compared to a weld line, the flow fronts come together at less than 135 degrees. A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. Weld lines appear as a result of the flow of molten plastic during the injection molding process. In injection molding weldlines are generated when two separate melt streams join either in multigated molds or as a consequence of flow around. Injection molding can be performed with only one of these. Some of these are listed below: Plastic warpage. It is important to investigate the weld line because the weld line area can induce potential failure of structural application. This is a video excerpt from our Problems & Solutions Course - Weldlines. These lines are formed when two or more flowing molten plastic streams meet and fuse together, creating a visible line on the surface of the molded part. Plastic Rapid Injection Molding is popular not only in low volume manufacturing but also in large quantities molding, it is the most common way to manufacture plastic parts. enough to each other to avoid weld line issues. Injection-molding machine is the Negri Bossi VE210-1700 with screw diameter 60 mm. The quality of the weld line can be improved through optimized processing conditions, increased mold and melt temperatures, and increased injection speed to reduce the viscosity of the polymer. These lines can occur due to variations in wall thickness, gate location, or the geometry of the part. Proceedings of ANTEC (2000), pp. In some cases, a weld line can also cause a loss of strength and impact resistance. The Solutions for Poor Welding Lines. Weld lines can be a weak spot and have therefore to be taken into consideration in part design. Therefore, more studies covering this subject are required in order to improve the insight regarding the mechanism involved in the formation of weld lines in extrusion and,From the so-produced materials, specimens with weld lines were produced according to the first test series, but varying the injection molding parameters only twice, between the best and worst settings found in the previous study with the polypropylene types with MFR 8 g/10 min, i. So today we are going to take a look at the five most common defects in injection molding and their solutions. Flow-induced filler orientation manifests in higher tensile prop-erties in the direction of flow compared to those normal to the direction of flow. Below is one of the examples: !NOTE: if the weld lines is important to the cosmetic surface of your part, please bring this up to your mold maker during quoting phase. They found that the weld line is a zone between 2 and 8 mm wide extending throughout the thickness in whichEffects of mold temperature and pressure on shrinkage 0. Plastic Injection Molding Process. In this regard, the plasticizing ability of the plastic injection moulding machine should be checked. when two or more melt flow fronts contact each other immediately after the cooling process. 22 shows how the weld lines are formed when the melt splits around core pins during the injection molding process. 1 Prediction of weld lines with injection molding simulation softwareReduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. Weld lines are visually undesirable and a plastic part is structurally weak at weld line positions. The flow fronts at different times (Fig. In the first stage, the two part halves are injection molded and then, in a second process step outside of the molding machine, they are welded together. For the production of these weld‐line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527‐2) and impact (ISO 179‐1/1eU. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. 1. What is weld lines. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. 2. S. If you have critical requirements for strength of knit lines, please call a Protolabs applications engineer at 877-479-3680 to discuss, or email at [email protected]. Google Scholar [10] S. 7 of the reference. Complexities in the design and intricate pathways in the mold can also create flash in injection molded parts. Sink MarksWeld lines, also known as knit lines, are a common defect in injection molding where two or more flow fronts of molten plastic meet but don’t properly fuse together. Weld line additionally called as knit line, is a defect that occurs when the injected plastic meets within a mold. Avient’s Zachary Alderman shares practical tips on designing and injection molding parts utilizing short-fiber reinforcements. A knit line in a plastic injection-molded part is created when two separate plastic flows meet within the mold and "resolidify" along their interface. Plastic Injection Molding Process. Part design features may cause a material flow to split and rejoin as it flows around design features in a mold. The structure is more complex with longer molding cycle . The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. As a result, the path of the injected melt can be extended, allowing the production of parts with more complex shapes and greater length. [1-2] investigated the weld line zone of injection molded glass-fiber-filled polypropylene (PP) composites. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. gas, which can cause blistering, as well as poor weld lines, warpage and the formation of cold slugs that affect filling and part mechanical properties. Int. Blistering 4. The most common method for the weld-line characterization is mechanical testing by means of a tensile or bend stage [6,7]. Problem: Weld lines are formed when plastic resin is forced around an obstruction in a mold tool and reforms on the side opposite the gate. Plastics manufactured by injection molding are meant to be durable and reliable, able to hold up to heavy use, high temperatures, or adverse conditions. As the plastic flows through the mold it forms a smooth and continuous flow front. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. Weld line, 5. Weld lines are weak regions in thermoplastic injection moldings, due to low molecular entanglement and unfavorable orientation. A weld line is a mark left on the surface of a plastic injected molded part. The results of. C. Weld Line defect analysis, the most common of many defects in injection moulding products. In this paper, aiming at the problem of weld line defects in the injec- tion process of a key phone panel, the injection process is optimized by using Moldflow and drop simulation. This customary mark is caused by differential rates of cooling in the resin where. Weld lines are a reality in the injection moulding of complex parts. 2) Vents in an injection mold should let the air out, but not the liquid plastic. An excess mold release is a major cause of weld line due to two variables: high pressure and speed. They occur when melt flow fronts collide in a mold cavity. 020 0. Weld lines may occur depending on the product shape and gate positions. Figure 2. Five injection molding process parameters, including mold temperature, melt temperature, packing pressure, injection. Weld lines in injection molding occur when two flow fronts meet and create a visible line on the surface of the molded part. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. In injection molding, a V-notch-shaped weld line is generated in the melt front meeting area. During the plastic injection molding process, one of the biggest challenges is. In the injection molding process, weld line regions occur when a molten polymer flow front is first separated and then rejoined. This month, in our FREE SimTech™ series of webinars, we will explore weld lines and how they develop. It is important to investigate the weld line because the weld line area can induce potential failure of structural application. 1. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties [3,4,5]. The position, length, and angle of weld lines are dependent on the. Runner Type Venting Plastic melt and mold temperature Injection speed and pressure Learn how to troubleshoot weld lines in injection molding. Specifically, injection-mold lines are often associated with poor mechanical strength. Weld lines are a common defect generated in injection molding, which apparently affects the performance of final products, but the available reports on carbon fiber-reinforced thermoplastics are. The thermo-rheological findings were used to investigate the sources of weld line weakness. In this study, the effects of injection temperature, injection pressure, and fiber cont. This study focus on the formation of. Wolfgang Homes, head of the applications department of Eurotool, a manufacturer of hot runner systems, clarified the two methods for IMI, noting that. Second, depending on the size of the overflow well, you get a little bit of flow melding together, and that helps strength so that you have some intertwining of the polymer chains. If weld lines are unavoidable due to multiple gates in a moulding, they should be positioned in the non-critical region. Weld lines have been one of the common defects puzzling the injection molding industry. , less than 0. Redesign the mold to. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms of weld-line, etc. They are the result of fundamental physical effects taking place inside of the mold tool cavity. Lesson 7: Meld and Weld Lines (Part Design) When plastic flows into an injection mold, the internal flow pattern depends on the part design, mold design, and processing factors. Our injection molding company is explaining what these imperfections are, why they can compromise. Weld lines are a kind of Achilles heel of plastics. Simulation of polymer molding filling process with an adaptive weld line capturing algorithm. also utilized the co-injection molding technique to study the flow of polypropylene at the weld line behind an obstacle in injection molding; the weld line can be seen clearly from the Fig. Try to gradually raise the mold temperature and barrel temperature. In the sense that the weld line is better formed before the resin. My polymer material selection courses 👉 Find Out About Plastics Blog👉 ht. Flow rate is 24 cm3/s. 2) Vents in an injection mold should let the air out, but not the liquid plastic. 000 0. The part becomes partially solidified and won’t sufficiently bond where the two halves meet, resulting in. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. The results showed that the tensile strength of PE remains unchanged in the presence of weld lines. Weld lines are one of the typical quality issues of injection molded parts. Weld lines appear on the molded part where molten plastic meets. • Reduce runner dimensions and maintain the same flow rate. The effects of fiber concentration has been studied in detail. Strength at weld the line location and warpage problem in injection molding plastic component were not new problems in injection molding industries. Weld lines are the unfavorable defect not only in normal injection molding process but in micro injection molding process. According to the studies, the most important factor to reduce weld lines is increasing the mold temperature. They decrease the. Flow marks in injection molding are defects that manifest as a line or series of lines forming a pattern different in color from the other parts of the molded material. Experimental Setup 2. If you have critical requirements for strength of knit lines, please call a Protolabs applications engineer at 877-479-3680 to discuss, or email at [email protected]. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. The molded plastic part may also appear to be rust-colored. Weld lines. Amongst weld line. If the large molded product is. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. injection molding, (b) weld line and meld line, and (c) injection sample size and shape. Zhao, X. This paper presents the. * Corresponding author, e-mail: fengsjpc@ku. Flow lines are lines, waves, or ring patterns that appear on the surface of a part, noted by their slightly different color from the rest of the piece. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. A poor knit line can cause only cosmetic blemishes or it can significantly weaken the structural integrity of a part. For example, filled resins and ABS are more likely to. When this fails to happen correctly, a weld line defect occurs. 8. 001 in . The effects of these two injection molding process parameters are explained in terms of their influence on the skin-core morphology observed on the fracture surfaces in the weld zone. The weld lines are an integral part of plastic injection molding and can seldom be prevented, even by specifically planning the mold with inserts for holes or the like. They. The hair-like weld line is the. These lines. (2) Causes & Countermeasures (See the table below) *Note: Flash also tends to occur when the injection pressure/speed are too high, but molding time is too long and mold temperature is too low. When the same pressure is maintained or lower than that, the drop in speed shall create the weld lines. View 08 DEFECTS & REMEDIES (61). Where the weld lines are, where the sink marks or voids will be, and how the part warps—all of these are determined by where the molten plastic is injected into the part cavity. Weld lines are the result of fundamental physical effects taking place inside of the mold tool cavity, they are common imperfection to be found in most plastic injection molded parts. To explore the formation of weld lines in injection molding, a. Adding vents, using overflows, or using porous metal. This occurs either due to injection through multiple gates or as a conse-รอยประสานของเนื้อพลาสติก Weld line ตอนที่1. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. This paper presents the. Weld lines in injection molding are frequently unavoidable. Figure 1 a illustrates how the weld line is produced when two melt streams merge during the final filling process. Thicker parts require more cooling time and can lead to air becoming trapped in the mold and weld / knit lines to form. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. 010 0. Some of the common fixes for weld lines include: Increase the resin temperature to ensure both sides of the weld line are liquid when colliding. Weld lines often generate mechanically weak areas, because of the unfavorable perpendicular orientation of the macromolecules, fibers and/or other fillers to the direction of the main flow. Instead, a line that looks like a seam forms. In this study, polypropylene (PP) was chosen as the processing material and a micro dog-bone tensile test sample was selected as the objective part. Multiple gating, splitting of the melt flow due to inserts in the cavity or through holes, as well as changes of thickness give rise to points within the structure where the flowing fronts will recombine and weld. Many works deal with weld lines and their dependence on processing parameters for conventional injection molding, but only a few works focus on the weld line in µIM. Additionally, you can get our free Design Cube, which will provide a physical aid to help understand how knit lines form as well as other injection molding design considerations. The simulated cold weld line length is consistent with the experimental one when a 115 °C mold temperature is adopted; with lower mold temperatures, the simulated lengths are smaller than the experimental ones—in accordance with the literature on the conventional injection molding process [26,27]—probably because of the definition adopted. Sink Marks Cause 3: Improper Pack or Hold Pressure. After that, the compounds were injection-molded into tensile samples with and without weld lines to. 13 shows the best gate location for which the weld lines . The thermo. You will have to confirm them before tooling. Thus, it is important to understand (i). Weld lines are also known as knit lines. Weld Lines-3 Ways for Detecting and Correcting. 18/06/2021. Weld Lines. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. In injection molded parts, there are 2 types of weld lines: The first type of weld mark is called cold-melt joints and is formed when the melt front enters the cavity with different gates. G. Three terms that often get mixed up are weld, meld, and knit lines. The default weld line result recognizes 135º as the maximum angle of collision and as that angle decreases, the severity increases as it. CrossRef View in Scopus Google Scholar [17] G. Provide a gas vent. To explore the formation of weld lines in injection molding, a. Weld lines, generated during injection molding, can significantly reduce the mechanical performance of structures. The resulting defects don’t stop at flash only. Weld Lines. (3) Adjust the temperature of the barrel and nozzle: the viscosity. The spreading mold release agent on the part cavity surface might eventually cumulate at the V-notch groove of the weld line after each injection molding shot. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms. Proceedings of ANTEC (2000) Google Scholar [9] S. Adjust the position of the gate and include a venting slot. (3) Adjust the temperature of the barrel and nozzle: the viscosity.